Tire pressure monitoring systems, remote keyless entry systems, passive entry/passive start, and or immobilizer systems for automotive applications are known to include one or more antennas positioned about the vehicle to receive radio frequency signals from RF based transmitters. Such transmitters may be in the form of tire pressure sensors that transmit tire pressure information to one or more of the antennas. The antennas, in turn, present the RF signal to a receiver in a controller. The controller processes such signals to determine moments in which one or more of the tires include a low tire pressure reading. The controller generally determines the location of the tire that includes a particular tire pressure sensor based on ID information contained within the RF signal.
The keyfob may be used in conjunction with a passive entry/passive start system. With passive entry, the controller generally determines which door to unlock based on the location of the keyfob with respect to the vehicle. With passive start, the controller determines whether the driver is in the vehicle based on the location of the keyfob. For example, the controller may be able to determine whether the keyfob is in the vehicle within the driver's zone.
A number of RF based vehicle operations (including those stated above) offered in vehicles today generally utilize multiple discrete antennas that are distributed throughout the vehicle to identify the location of the RF transmitter with respect to the vehicle. Along with such discrete antennas, elaborate wiring and tuning is generally needed to identify the location of the RF transmitter with respect to the vehicle.